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Home >> Toyota >> 1995 >> T100 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 3.4L >> Diagnostic Testing >> Code P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Connect scan tester to DLC3 connector. See Figure. Start vehicle and warm engine to normal operating temperature. Turn on scan tester. Monitor each oxygen sensor. Snap accelerate engine 3 times. Sensors should indicate a rich signal (.45 volt or more).
  2. If a rich signal is indicated for both sensors, replace ECM and retest. If either sensor does NOT display a rich signal, inspect circuits between ECM and suspect sensor for open or short circuits. See wiring diagram in the WIRING DIAGRAMS - 3.4L article. Repair as needed. If circuits are okay, replace oxygen sensor and retest.
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